Trichoderma rugulosum M.S. Park, S-Y. Oh & Y.W. Lim

Index Fungorum number: IF824663; Facesoffungi number: FoF04461

Etymology: The specific epithet refers to the wrinkle in colony reverse on PDA.

Holotype: SFC20180301-001

Colour codes follow: Methuen Handbook of colour (Kornerup and Wanscher 1963).

Sexual morph: Undetermined. Asexual morph: Hyphomycetous. Conidiophores symmetry, branches mostly paired. Phialides typically formed in whorls of 3–4, ampulliform to lageniform, 5.9–10.3(−10.5) × 2.1–3.6(−3.9) μm, l/w 1.9–3.7(−3.8), (1.2 −)1.3–1.9 μm wide at the base (n = 30). Conidia green, smooth, globose, subglobose or broadly ellipsoidal, (2.5–)2.6–3.2 × (2.3–)2.3–2.9 μm, l/w 1–1.2(−1.3) (n = 30).

Culture characteristics: On CMD after 72 h, colony radius 10–14 mm at 15 °C, 24–29 mm at 20 °C, 62–69 mm at 25 °C, 69–75 mm at 30 °C; colonies on CMD fill a 90 mm diam. Petri dish within 4 days at 25 °C. Colony hyaline, radial, mycelium loose, indistinctly zonate, and aerial hyphae more abundant in distance from the inoculum. Conidiation starts after 3 days, with deep green (M. 27E8) or greyish green (M. 27c4) conidia forming in pustules. No chlamydospores observed. No distinct odour. Agar not pigmented. On PDA after 72 h, colony radius 9–11 mm at 15 °C, 13–21 mm at 20 °C, 38–43 mm at 25 °C, 22–42 mm at 30 °C, colonies on PDA fill a 90 mm diam. Petri dish within 6 days at 25 °C. Colony radial, mycelium dense, zonate, aerial hyphae abundant, spreading uniformly throughout the colony, forming wrinkles in distance from the inoculum in a reverse colony, at 30 °C colony radial, mycelium dense, with a wavy margin. Conidiation starts after 3 days, effuse in aerial hyphae or in densely disposed granules, more abundant in 4–5 concentric rings, yellowish green (M. 30B8). No chlamydospores observed. No distinct odour. Olive yellow (M. 3C8) pigment diffusing into the agar. On SNA after 72 h, colony radius 3–6 mm at 15 °C, 7–11 mm at 20 °C, 14–29 mm at 25 °C, and 10–21 mm at 30 °C; colonies on SNA a 90 mm diam. the Petri dish within 8–9 days at 25 °C. Colony hyaline, radial, mycelium loose, not finely zonate, aerial hyphae common. Conidiation starts after 3 days, with deep green (M. 27E8) or yellowish green (M. 30B8) conidia forming in pustules, pustules forming in 2–3 concentric rings.

Material examined: REPUBLIC OF KOREA, Jeju Province, Chuja-do Island, isolated from Chondria crassicaulis Harvey, September 2017. M.S. Park, F181 (SFC20180301-001, holotype), ex-type living culture KACC 48485; ibid., Chuja-do, isolated from Sargassum thunbergii (Mertens ex Roth) Kuntze, September 2017, M.S. Park, SFC20180301-002.

GenBank numbers: ITS = MH050353, RPB2 = MH025986, TEF1-α = MH025984.

Notes: Trichoderma rugulosum is isolated from Chondria crassicaulis and Sargassum thunbergii (seaweeds) in South Korea. Morphologically and phylogenetically, T. rugulosum is closely related to species in the T. harzianum complex. However, these species have faster growth at 30 °C on SNA (32–70 mm on SNA after 3 days). T. rugulosum shows a wrinkle in colony reverse on PDA at 25 °C and a wavy margin on PDA at 30 °C, features not seen in members of the T. harzianum complex.

Figure 1. Trichoderma rugulosum (SFC20180301-001, holotype). a Colony on CMD after 72 h. b Colony on PDA after 72 h. c Colony on SNA after 72 h. d Colony on PDA after 72 h from the reverse. e–g Conidiophores. h Conidia. Scale bars: e–h = 20 μm